1. Field of the Invention
The present invention relates to a carburetor having an electrically-operated automatic choke system that is primarily applied to a general purpose engine, and particularly, to an electrically-operated automatic choke-system that includes an electric motor, a transmission device for transmitting a driving torque of the electric motor to a choke valve of the carburetor in directions to open and close the choke valve, and an electronic control unit for controlling operation of the electric motor.
2. Description of the Related Art
Such an electrically-operated automatic choke system of a carburetor is known from, for example, Japanese Patent Application Laid-open No. 58-155255.
Since a conventional electrically-operated automatic choke system operates so that a choke valve is held at a fully open position when an engine is in a hot running state, the fully open state of the choke valve is maintained even after the engine stops running. Therefore, when the engine is cold-started, an electric motor operates to fully close the choke valve.
However, in the case where the system has no battery and an electric motor is operated using power generated by a generator driven by an engine, or, in the case where the system has a battery but the amount of electricity stored in the battery is insufficient while being cold-started, even if the electric motor does not operate, the choke valve remains open, and a rich air-fuel mixture suitable for a cold start cannot be generated in an intake path of the carburetor, making it difficult to start the engine.